Abstract: Earth’s ionosphere, the high-altitude ionized portion of its atmosphere, is produced by solar
EUV radiation and bombardment by energetic particles. At altitudes where the ionospheric
plasma is most dense, the neutral atmosphere is still several orders of magnitude higher in
concentration; additionally, owing to the high conductivity of the plasma in the direction parallel
to the geomagnetic field it is electrically connected to the overlying magnetosphere and solar
wind. As such the ionosphere represents an open system — mass, energy, and momentum
travel relatively freely amongst the atmosphere-ionosphere-magnetosphere (AIM). When
coupled with the tendency for the ionospheric dynamics at multiple spatial and temporal
scales, this presents enormous challenges for modeling and theoretical studies: simulations of
the global ionosphere cannot capture processes of known importance, while local-scale highresolution
models have boundaries across which complicated interactions occur.
This colloquium is focused on initiation and progression of fluid-scale ionospheric plasma
instabilities resulting from (AIM) coupling process. Such instabilities have been implicated as a
major source of small scale plasma structures and attendant radio scintillation and affect radio
propagation through in a range of technologically important bands from HF through L-band.
We summarize high resolution modeling studies of high-latitude shear- and gradient-related
plasma instabilities driven by magnetospheric dynamics as well as equatorial instabilities
seeded by lower atmospheric disturbances (i.e. weather-related phenomena). A number of
challenges arise in these modeling studies and we discuss extant needs and potential future
directions.

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Meeting ID: 949 9307 4317
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